Honestly, the only one who really doesn't fit here is Malfoy. Ron and Hermione in Hufflepuff/Ravenclaw is practically half canon, while Slytherin was the Sorting Hat's first choice for Harry.

But I just can't see Malfoy as anything but a Slytherin. He is waaaay too opportunistic and self-serving, and he buys completely into the blood purity racism that taints the house in his era.

Well, if he got it into his head to be his own man, not live in his father's shadow by relying on his wealth and status...

From the commentary, the artist said this AU was because of Draco's actor.

Tom Felton seems like a loveable person. Plus, he auditioned to play Harry and Ron before landing Malfoy role.
I didn't follow the movie series and its actors that much tho~